Spreading itself across our waterways like a lush green carpet is one of nature’s enemies, growing up to 20cm a day and suffocating native plants and fish.
Floating pennywort, originally from America, is an invasive plant that arrived in the UK in the late 80s and has since caused havoc in the environment.
As well as having a harmful impact on the biodiversity, it is also restricting our flood alleviation structures in the rivers.
The plant is prominent in the east, in particular along the Chelmer and Blackwater catchment in Essex, but thanks to good partnership work that has developed in recent times, we are making progress.
I first became interested in this subject while studying at Glamorgan University in 2003 where I began researching its detrimental effects on invertebrate and fish populations.
Now as part of my role as a fisheries officer for the Environment Agency, I am often involved in clearance operations to rid rivers and canals of this fast-growing weed.

It usually begins to spread around late April/May and it is possible that it may be worse this year due to the warm winter we experienced, meaning it hasn’t died back as it usually does during cold spells.
One of the areas most affected was the Blackwater canal near Chelmsford and Maldon, which had been taken over by the invasive plant. It is thought that someone emptying the contents of their fish tank into the river probably caused the pennywort's arrival in the upper Chelmer and Can rivers.
Some parts of the canal were completely covered back then, which severely reduced oxygen. This meant recreational activities such as fishing and boating were unable to take place and there was a risk to livestock, dogs and human health.
In 2004/05 the Environment Agency, the Canal Trust, and volunteer groups came together in a huge effort of manual clearance and herbicide treatment to help eradicate the weed. Since then our relationship with community groups such as fishing clubs and the Rambler’s Association, has grown, which has improved our resources to tackle the issue.
Sections of the Blackwater catchment have experienced new growth since then and although this is only limited to small pockets, the potential for spread is high.
This year I worked with our operations team to remove floating pennywort from Dock River at Parkeston. Due to the habitat and fish populations that are supported by the weed, spraying and removing it by using the large weed cutting boat would have been extremely harmful, possibly resulting in fish deaths. Instead we used small boats to drag the weed to one removal point, thereby minimising water quality issues and preventing the need to cut back the important fish and water vole refuge.
The only way to prevent growth is early intervention so it is vital that people who spot this in the waterways alert us as soon as possible.
By stopping the spread at an early stage, it is much more cost effective than attempting to control species once it has become established.
However we need the public’s help to do this. Thanks to our PlantTracker app, people can now easily identify it and then report it to our 24-hour incident hotline as soon as possible on 0800 80 70 60.
To download the plant tracker app click on the here
10 comments
Comment by Briton Walker posted on
I have recently moved to a house on the River Wey KT13*XF and the river has a growing problem with Pennywort. I sopoke to the Environmental Authority who said as riparian owner it was my job to clear it. I said it might be the whole way from Weybridge to Guildford with hundreds of owners. The thenput me to the pollution department who said I must report it to the police.
I had experience with invasion of Water hyacinth and covering tropical rivers from bank to bank and experimented with composting but little job.
If you would like to talk my phone is 07940762680
Briton Walker
Comment by kathrynbooth posted on
Hello, We will take reports of Floating Pennywort in the:
North East area
the Fossdyke Navigation in the Lincs and Northants area
We don't take reports for any other areas as it remains the landowners responsibility to control the plant.
For the North East, the Environment Agency and the Rivers Trust are co-ordinating the eradication work which started in April 2012 and will last for approx 3 years. For the Fossdyke Navigation we're working with the Canal and River Trust to eradicate the species.
For any other area, customers will need to manage the plant themselves.
Eileen
Comment by Tom Berman posted on
Tom Berman:
I live by the Wargrave reach of the Thames, where Floating Pennywort arrived in October 2017. I immediately reported it to the Environment Agency, who first said plants were nothing to do with the EA and told me to talk to Natural England ! Secondly they said that the problem was “ unreportable” because “it is the landowners responsibility”. This is complete nonsense and the EA must stop it and accept their responsibility. By definition this is a floating weed and the EA has known about it for years and has allowed it to float down from the Reading area of the Thames to Sonning, to Shiplake and now to Wargrave. Next stop Henley. The fact that the stuff sometimes attaches itself to the bank, does not make it the riparian landowner’s responsibility. I have written to James Bevan, the EA Chief Executive, under whose watch this disaster has occured. No answer as yet (whatever the crisis, this bureaucracy has a charter that gives itself 10 working days before it responds to anything).
Bermantomjanet@aol,com. Tel 0118 940 3319
Comment by Tony Elliott posted on
Phone 0800 80 70 60 to report out breaks of Pennywort to the EA .
I am Chairman of ousefishing.com and we are working on the problem with them on our waters .
It is not a landowners responsibility, the EA have a legal duty to maintain and improve the environment.
Pennywort removes light and Oxygen from the water and will eventually kill off the invertebrates who are an essential part of the chain of life in our rivers .
Comment by d.g.stuart posted on
There seems to have been little done on the river Wey since Briton Walker's comments nearly three years ago (24/10/2017).
Yesterday, 7th., July, 2020, the river Wey was at some points (three) between Thames Lock and Send, impossible to navigate without danger of having one's propeller fouled by the weed. Expanses of floating pennywort are seldom out of sight as one progresses up river.
Surely it's about time that the the Jobsworths Brigade, whoever they are, stopped passing the buck, took responsibility for this mess and started sorting it out.
Please reply tour reasons for this inaction, e-mail address beow.
Douglas Stuart. Guildford.
Comment by d.g.stuart posted on
There seems to have been little done on the river Wey since Briton Walker's comments nearly three years ago (24/10/2017).
Yesterday, 7th., July, 2020, the river Wey was at some points (three) between Thames Lock and Send, impossible to navigate without danger of having one's propeller fouled by the weed. Expanses of floating pennywort are seldom out of sight as one progresses up river.
Surely it's about time that the the Jobsworths Brigade, whoever they are, stopped passing the buck, took responsibility for this mess and started sorting it out.
Please reply tour reasons for this inaction, e-mail address beo
I advised of this matter today. No reply received.
Douglas Stuart. Guildford.
This e-mail is not an advice but it is a FORMAL COMPLAINT.
No further explanation and I shall now seek the support of my M.P.
DGS
Comment by eileenroffe posted on
Good morning - I have forwarded your blog post/complaint to the complaints team for their action - Eileen
Comment by Sandra Stevenson posted on
We have the same problem on the river Frays at Uxbridge. The Pennywort is in its third or fourth year now and absolutely nothing has been done. I too was told of my responsibility under the riparian thing but at 74 I’m a bit old to don waders! The silt underneath is also rising fast and a winter of heavy rainfall will cause flooding. Guy from the environment agency was no help at all. Am trying to get a volunteer group together but not sure where to start. So sad all the ducks and birds have had to move on. Good luck with your area. Regards Sandra Stevenson.
Comment by Chloe Ellis posted on
Hello, when operations to remove Pennywort are decided, is an Environmental Impact Assessment carried out? I would love to learn more about the process if possible, as im currently a 3rd year geography student looking to write a report on the application of such EIA for invasive plant removal. Thanks in advance
Comment by eileenroffe posted on
Hello Chloe, please email us with the area you would like to work in as we do have opportunities for students to work with us. During the Covid 19 pandemic this may be put on hold but email us at: enquiries@environment-agency.gov.uk - best wishes - Eileen